Method of treating sour hydrocarbon oil



2 Sheets-Sheet l uw NN, QN

@et 69 1936., w. v. @VERBAUGH METHOD OF TREATING SOUR HYDROCARBON OIL Filed:k Dec. 27, 1932 @w www Ct. 6, 193., W, v QVERBAUGH 2,056,61

METHOD OF TREATING SOUR HYDROCAR-BON OIL Filed DeC. 27, 1952 2 Sheets-Sheet 2 Patented Oct. 6, 1936 UNITED STATES PATENT OFFICE METHOD OF TREATING SOUR HYDRO- CARBON OIL Walter V. Overbaugh, Fishkill, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application December 27, 1932, Serial No. 648,856 3 Claims. (Cl. 196--33) This invention relates to a method of treating into the reactionin order'to facilitate the conpetroleum hydrocarbon oils and more particu- Version of the mercaptans.

larly to a process of sweetening light hydrocar- I have found that if the sour naphtha is diluted bon distillates prepared by the distillation or with varying amounts of naphtha which has al- 5 cracking of petroleum. ready been sweetened and the resulting solution 5 More specifically, my invention relates to a is subjected to treatment, with either an alkaline method of sweetening naphthas containing unsodium plumbite solution or a suspension of lead desirable odorous sulfur compounds wherein the sulde in an alkaline solution, that the sour hyuntreated naphtha is mixed with a varying prodrocarbons may be sweetened much more rapidly l portion of sweetened naphtha to form a solution and much more efficiently. For example, when l0 and then subjecting this solution to the action of treating a sour naphtha which requires one baia sweetening reagentV which may either be an rel of a standard sodium plumbite solution for alkaline solution of sodium plumbite, a suspeneach 250 barrels of naphtha, I have found that sion of lead sulde in an alkaline solution or any five times as much naphtha may be sweetened l other reagent ycapable of transforming mercapby recirculating from one-half to ten volumes of 15 tans into disulfides. sweetened naphtha to each volume of sour Untreated naphthas contain, among other sulnaphtha. fur compounds, a certain group known as mer- I have found that the greatly increased efficaptans. These compounds impart to the naphciency may also be obtained'by treating the o0 thas in which they are present extremely unnaphtha in accordance with my invention with 20 pleasant odors as well-as rendering the naphthas an alkaline suspension of lead sulfide. In this corrosivev to certain metals. In rei'inery termicase, the reagent may be used for sweetening unnology such naphthas are spoken of as being limited quantities of sour naphtha, the only limisour. tation imposed appearing to be the loss of lead 95 Various methods have been developed for suliide and caustic solution due to the carrying- 25 sweetening sour naphthas. The most important over effect. By replenishing' the quantities of of these methods comprises reacting the sour lead sulfide and alkaline solution from time to naphthas with alkaline solutions of sodium time, it is possible to carry on the process conplumbite whereby the mercaptans are converted tinuously over an extended period of time.

to the corresponding oil-soluble lead mercaptides. My invention may be used in any of the con- 30 'I'he last named compounds are then in turn conventional treating SyStemS for sweetening S0111 verted to the disuldes by treating the naphtha hydrocarbon oils. Not only does the invention solution of the lead mercaptides with a proper find applieetOn in the usual parallel lOW treat amount of elementary sulfur. The following ing Systems but also in those systems where the equations illustrate generally the above described S0111' naphtha and treating reagent are flowed 35 reactions; countercurrently.

Rs Suitable forms of apparatus for carrying on 2RvSH+NmPbOH \Pb+2NaOH my invention are shown in the accompanying drawings in which: 40 RS Fig. 1 discloses an apparatus suitable for treat- 40 RS ing naphtha with a parallel ow of sweetening \Pb+s- 1,Pbs+ i reagent.

R-s Fig. 2 discloses an apparatus in which naphtha RS may be treated with a countercurrently flowing stream of sweetening reagent.

Fig. l is a diagrammatical view showing an ap- 45 The sweetening of sour hydrocarbons may also be brought about by treating them with suspenparatus which may be used for the concurrent sions of lead sulfide in ialkaline solutions. Foresweeting of a sour naphtha with a suitable I.e most among the treating suspensions 1s one of agent Fig' 2 is a diagrammacal View of an I eafl Sulde m Sfdlum hydroxlde' Ilfsome Cases apparatus suitable for countercurrent treatment 50 it is found possible to effect an eflicient converof sour naphtha with a, sweetening reagent-, sion of mercaptans to the corresponding disul- In Fig 1, the numeral m designates a Storage fides by Simply agitating the Sour hydrocarbon tank for sour naphtha. This tank is fitted with oil with the treating Suspension. In some operaa drawoff line ll controlled by the valve I2 which tions, it may be desirable to introduce oxygen enters the intake side of the charge pump I3. 55

This pump discharges through the line I4 through the valves I9 and 20 into the mixing device 2|. There is i'ltted around the valve I9 the by-pass line I6 controlled by the valves I5 and I8 which line has interposed in it the sulfur pot I1.

The numerals 22 and 23 designate storage tanks for doctor solution and suspension of lead sulde in caustic soda solution respectively. Each of these tanks is equipped with a drawofl line indicated respectively by the numerals 24 and 25 controlled by the valves 26 and 21. These drawoi lines are connected to a common line 28 which leads to the intake .side of the pump 29.

This pump discharges through the line 30 controlled by the valve 3| into the four-Way tting 32 through the line 33 controlled by the valve 34 into the four-Way iitting 35 and thence through the line 36 controlled by the valve 31 which connects with the intake side of the circulating pump 38. This pump discharges through the line 39 controlled by the valve 40 into the line I4 lat a point intermediate the valve 20 and the input side of the mixing chamber 2|.

The mixing device 2| discharges through the line 4I controlled by the valve 42 into the settling chamber 43. This settling chamber, which may with advantage be provided with a conical bottom, is equipped at its lowermost point with a drawoi line 44 controlled by the valve 45 which enters the four-Way fitting or cross 35, While it is tted at its uppermost point with a liquid drawoff line 46 controlled by the valves 41 and 48 and which enters the settling chamber 49 at an intermediate point.

The settling chamber 49 may advantageously be of the same construction as the settling chamber 43. It is iitted at its bottom with a drawoff line 50 controlled by the valves 5I and 52 which line is connected to the cross fitting 32. The cross iitting 32 is connected in turn with the spent treating reagent tank by means of the line 53 controlled by the valve 54. The line 50 is fitted at a point intermediate the valves 5| and 52 with a line 51 controlled by the valve 58 which connects the line 50 with the cross iitting 35.

The top of the settling chamber 49 is equipped with a drawoff line 59 controlled by the Valves 60 and 6I which line connects the settling chamber to thel storage tank 62 for treated naphtha. There is manifolded to the line 59 intermediate the valves and 6I the line 63 controlled by the valve 64 which enters the line 36 at a point intermediate the valve 31 and the intake side of the pump 38. At a point between the valves 41 and 48, the line 46 is joined to the line 63 by means of the line 65 controlled by the valve 66.

In a typical operation of the processemployed by my invention in connection with lthe apparatus shown in Fig. l, sour naphtha is drawn from the storage tank I0 and delivered to the intake side of the pump I3. This pump delivers the naphtha under a'suitable pressure throughthe line I4 into the mixing device 2|; In `order to permit of the solution by the untreated naphtha of a suiiicient quantity of sulfur, a controlled now of the naphtha is by-passed through the sulfur pot I1.

A charge of treating solution is introduced into the system from either one of the tanks`22 or 23 by means of the pump 29 through the lines 30, 33 and 36 and' the pump 38. The principal portion of this treating solution accumulates in the settling chamber 43, the lower portion of which serves as a storage therefor.

In beginning the operation of the process. sour naphtha and a proportioned amount of treating solution are mixed in the mixing device 2|. The mixture formed therein is discharged through the line 4I and the valve 42 into the settling chamber 43 wherein the treated naphtha separates quite extensively from the treating reagent. 'I'he latter settles to the bottom in a pool while the treated naphtha is drawn off from the top through lthe line 46 and discharged into the settling chamber 49. Here the remaining traces of treating reagent settle out and the clear treated naphtha is drawn olf from the top through the line 59 and delivered to the storage tank 62. When this condition has been established, that is to say, when treated naphtha is discharged from the top of the settling chamber 59, a quantity of the treated naphtha is by-passed through the line 63 and delivered to the intake side of the circulating pump 38. This circulating pump discharges the treated naphtha into the line I4 through which a ow of sour naphtha is maintained. Simultaneously, a proportioned amount of treating reagent is drawn ol from the bottom of the settling chambers 43 and 49 and together delivered to the mixing device 2| a mixture of treated naphtha, sour naphtha and treating reagent and this mixture after vigorous agitation is introduced into the settling chamber 43. The rates of ilow o'f the various streams are so regulated by the control of the various valves that the overflow from the settler 49 is at all times maintained sweet while using the minimum amount of treating reagents.

In Fig. 2, the numeral I0 designates a storage for sour naphtha. This tank is equipped with a drawoil' line I I controlled by the valve I2 which connects the tank I0 with the intake side of the pump I3. This pump discharges through the line I4 controlled by the valves I9 and 20 into a mixing device 2|. There is fitted about the valve I9 a by-pass'line I6 in which there is interposed a sulfur pot I1. This by-pass line is controlled by the valves I5 and I8. The mixing device 2| discharges through the line 10 controlled by the valve 1I into the settling chamber 12.

The settling chamber 12 is tted at its uppermost point with a drawoif line 13 controlled by the valve 14 which connects the settling chamber with the mixing device 15. This mixing device is provided with a line 10 controlled by the valve 11 which enters the discharge side of the pump 18. The intake side of this pump is connected with a tank 8| for treating reagent through the line 19 controlled by the valve 80. This tank ls connected by means of the line 82 controlled by the valve 83 with the bottom of the settling chamber 12. 'I'he line 82 is connected with the line 19 by means of the branch line 99 controlled by the valve |00. Into this branch line at a point intermediate the line 82 and the valve |00 there is tted the drawoi line |02 controlled by the valve |03 which leads to a storage (not shown) for spent treating reagent. By the proper manipulation of the necessary valves, it is possible to either circulate treating reagent or to draw olf treating reagent which has become spent.

The mixing chamber 15 discharges through the line 84 controlled by the valve 85 into the settling chamber 86. The bottom of this settling chamber is provided with a drawoff line81 controlled by the valver88 which connects through the pump '89 and the Valve 90 with the mixing device v,2|. The top of the settling chamber 86 is equipped with a drawoff line 9| controlled by the valves 92 and 93 which leads to the treated naphtha stor- 75 age tank 98. There is manifolded to the line 9| at a point intermediate the valves 92 and 93 the line 94 controlled by the valve 95 which leads through the circulating pump 96 and the valve 91 into the line I4 at a point intermediate the valves I9 and 20.

In a typical operation of the process in connection with the apparatus shown in Fig. 2, a sour naphtha, that is, a naphtha containing undesirable mercaptan bodies, is drawn from a storage tank I8 by the pump I3 and delivered by this pump under a suitable pressure into the line I4 which leads to the mixing device 2|. A portion of the sour naphtha may be by-passed through the sulfur pot I1 where enough sulfur is dissolved by the naphtha to permit of the subsequent decomposition of the lead mercaptides.

There is also introduced into the mixing device 2| a quantity of naphtha which has already been sweetened and which is recycled from a subsequent step in the process. The mixture of sweetened and unsweetened naphtha is thoroughly agitated with treating reagent delivered from the bottom of the settling chamber 8B. In this manner the sour naphtha is partly sweetened and the mixture of treated naphtha, partly treated naphtha and treating reagent is delivered into the settling chamber 12 wherein the separation of the treating reagent from the naphtha is brought about. The treating reagent which settles to the bottom of the settling chamber is permitted to iiow through the line 82 controlled by the valve 83 into the treating reagent storage tank 8|. The supernatant layer of partly treated naphtha which separates out in the settling chamber 12 is drawn off from the top of the chamber through the line 13 controlled by the valve 14 and delivered into the mixing device 15 wherein it is agitated with treating reagent delivered from the storage tank 8| by means of the pump 18. By this treatment, the last traces of mercaptans are removed and the naphtha is completly sweetened. The mixture of treated naphtha and treating reagent is delivered to the settling chamber 86 through the line 84 controlled by the valve 85. In this settling chamber, a complete separation of the treated naphtha from the treating reagent takes place. The treated naphtha is drawn off from the top of this chamber and delivered to the storage tank 98 through the line 9| controlled by the valves 92 and 93. Facilities are provided in the form of a line 94 controlled by the valve 95 whereby a portion of the treated naphtha may be recycled to the mixing device 2|.

The treating reagent which settles out as a pool in the bottom of the settling chamber 86 is drawn off in a controlled stream through the line 81 controlled by the valve 88 and is circulated to the mixing device 2| by means of the pump 89.

In carrying o-ut the herein disclosed invention, it may be advantageous to commence treating with the usual alkaline solution of sodium plumbite. After this treating reagent has been in use for a certain length o-f time, it may be found that the caustic soluble lead has been reduced to a value approaching Zero. Ordinarily, it is found necessary to draw 01T the reagent when it has becO-me spent to such an extent and to replace it with a fresh alkaline solution of sodium plumbite. I have found it desirable in some cases to continue using the spent doctor solution which consists of caustic soda solution and lead sulfide and, if necessary, to subject it to a heat treatment or reaction with oxygen whereby the quantities of caustic soluble lead may be increased to a value approaching the original concentration.

In the treatment of certain naphthas which contain low molecular Weight mercaptans, that is to say, mercaptans which are highly reactive, it is unnecessary to reactivate the spent doctor solution in which case the reaction may be carried out while using simply a suspension of lead sulde in a water solution of sodium hydroxide or other alkaline solution.

Various ratios of sweetened to sour naphthas may be maintained in carrying out the treating reaction. It is obvious that if the quantity of treated naphtha which is recirculated is exceedingly large, a diminution in the output of a treatingi battery will result. This is directly due to the fact that there is a critical flow rate which may not be exceeded in any of the iiow chambers if a suitable separation of the naphtha from the treating reagent is to be effected. If the rate of iiow through the settlers is maintained near the critical flow rate, an undesirable and uneconomical carrying over of treating reagent by the sweetened naphtha results. I have found that in most treating operations a ratio of sweetened naphtha to one part sour naphtha of from one-half to ten is the most effective range. However, greater or smaller ratios than these may be found necessary in the treatment of various naphthas.

Obviously many vmodiiications and Variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method of treating sour hydrocarbon oil which comprises mixing the sour hydrocarbon oil with from one-half to ten times its volume of sweetened oil to form a mixture and then agitating the mixture, in the presence of sulfur, with a treating reagent selected from a group consisting of an alkaline solution of sodium plumbite and a suspension of lead sulfide in an alkaline solution, subjecting the reaction mixture to settling, drawing oif the sweetened oil and returning the treating reagent to further reaction.

2. A method of treating sour hydrocarbon oil which comprises mixing the sour hydrocarbon oil with from one-half to ten times its volume of sweetened oil to form a mixture and then subjecting the mixture to sweetening treatment in the presence of sulfur and an alkaline solution of sodium plumbite as a treating reagent until the caustic soluble lead content of the treating reagent has been converted into lead suliide and then continuing to treat a mixture consisting of sour hydrocarbon oil and from one-half to ten times its volume of sweetened oil with the lead suliide suspension thus formed and sulfur.

3. In the method of sweetening sour hydrocarbon oil wherein a sour hydrocarbon oil is treated, in the presence of sulfur, with a sweetening reagent selected from the group consisting of an alkaline solution of sodium plumbite anda suspension of lead sulfide in an alkaline solution in a treating Zone, the step consisting in recirculating sweetened oil to the treating zone in sufcient quantity that the ratio of sour naphtha to sweetened naphtha is within the limits of 121/2 and 1:10, whereby the rapidity and eiiciency of the sweetening process is improved.

WALTER V. OVERBAUGH. 

